The invention pertains to a high pressure coolant tube utilized to fluidly connect a tool holder to a clamping unit assembly and a tool body-high pressure coolant tube assembly. More specifically, the invention pertains to a high pressure coolant tube that allows for the delivery of coolant under higher pressures (e.g., 500 bar) than heretofore used (80 bar) without detrimental consequences such as the backflow contamination of the clamping unit assembly, and a tool body-high pressure coolant tube assembly.
Metal cutting tools for performing metal working operations generally comprise a cutting insert having a surface terminating at a cutting edge and a tool holder formed with a seat adapted to receive the insert. The cutting insert engages a workpiece to remove material, and in the process forms chips of the material. Excessive heat at the insert-chip interface can negatively impact upon (i.e., reduce or shorten) the useful tool life of the cutting insert. For example, a chip generated from the workpiece can sometimes stick (e.g., through welding) to the surface of the cutting insert. The build up of chip material on the cutting insert in this fashion is an undesirable occurrence that can negatively impact upon the performance of the cutting insert, and hence, the overall material removal operation. A flow of coolant to the insert-chip interface will reduce the potential for such welding. It would therefore be desirable to reduce excessive heat at the insert-chip interface to eliminate or reduce build up of chip material. As another example, in a chipforming material removal operation, there can occur instances in which the chips do not exit the region of the insert-chip interface when the chip sticks to the cutting insert. When a chip does not exit the region of the insert-chip interface, there is the potential that a chip can be re-cut. It is undesirable for the milling insert to re-cut a chip already removed from the workpiece. A flow of coolant to the insert-chip interface will facilitate the evacuation of chips from the insert-chip interface thereby minimizing the potential that a chip will be re-cut. There is an appreciation that a shorter useful tool life increases operating costs and decreases overall production efficiency. Excessive heat at the insert-chip interface contribute to the welding of chip material and re-cutting of chips, both of which are detrimental to production efficiency. There are readily apparent advantages connected with decreasing the heat at the insert-chip interface wherein one way to decrease the temperature is to supply coolant to the insert-chip interface.
A machine tool includes a spindle that includes a clamping unit assembly. The clamping unit assembly clamps (or affixes) a tool body to the spindle. The tool body carries the cutting insert in one fashion or another. In a machine tool that provide for the delivery coolant to the cutting insert, each one of the tool body and the clamping unit assembly contains a bore through which coolant can flow. Because the tool body and clamping unit assembly are separate components, in order to achieve satisfactory coolant flow to the cutting insert, the coolant must be able to flow from the clamping unit assembly to the tool body. Heretofore, a coolant tube has been used to fluidly connect the tool body and the clamping unit assembly. Exemplary coolant tubes are described in United States Patent Application Publication No. US2005/0095075 to Schweizer et al., WIPO Publication No. WO/2010/046046 A2 to Chi-Ron Werke GmbH & Co. KG, and U.S. Pat. No. 6,059,712 to Winkler et al.
While coolant tubes have functioned in an acceptable manner at pressures equal to about 80 bar, heretofore, one drawback has been that earlier coolant tubes have not been able to satisfactorily accommodate the delivery of coolant at high pressures (e.g., 500 bar). One detrimental result with using earlier coolant tubes at high pressures has been backflow that contaminates the clamping unit assembly. Thus, it would be highly desirable to provide a high pressure coolant tube, as well as a tool body-high pressure coolant tube assembly, that achieves satisfactory performance at coolant pressures in a pressure region equal to about 500 bar. It would be highly desirable to provide a high pressure coolant tube, as well as a tool body-high pressure coolant tube assembly, that when subjected to coolant pressures in a pressure region equal to about 500 bar, the coolant tube does not allow for backflow contamination of the clamping unit assembly.